Inner capsid particles of reovirus and rotavirus. Reovirus cores, particles of about 700 [unreadable] diameter, crystallize in space group F432, a=1249 [unreadable]. The crystals diffract to 3.5 [unreadable] resolution. We have used dual Fuji images plates, mounted in a special cassette on the F1 beamline, to collect data in 0.1 degree oscillation frames. Lower resolution data have been measured using the Quantum 4 detector. We have assembled a relatively complete data set, and we have commenced calculations using cryoEM images to determine initial phases. We have also screened for heavy-atom derivatives. The rotavirus ICPs, similar in size and function, crystallize in space group P212121, a=700 [unreadable], b=1000 [unreadable], c=1400 [unreadable]. We have collected a partial high-resolution data set, using dual image plates, as well as a much more complete lower-resolution data set, using the Quantum 4 detector. Human transferrin receptor. We have determined the structure of the transferrin receptor ectodomain to about 3.2 [unreadable] resolution, using data collected from unliganded crystals as well as crystals soaked in SmCl3 and in the platinum compound PIP. The space group is P212121, a = 105, b = 217, c = 364 (8 polypeptide chains per asymmetric unit). The Quantum 4 detector on F1 was important for obtaining sufficiently accurate data. The 70 kDa polypeptide chain folds into three domains, one of which mediates dimerization. Another domain bears a striking and unanticipated similarity to certain metalloproteases. The structure is being refined. Clathrin terminal domain. We have determined the structure of the 50 kDa N-terminal domain of clathrin. There is a globular portion, with a 7-blade beta propeller fold, and a stem-like region based on an alpha-helical zig-zag. HIV reverse transcriptase. We have determined the structure of a template/primer/dNTP complex of HIV reverse transcriptase at 3 [unreadable] resolution, using data collected at F1 with the Quantum 4 detector. The crystals are in space group P212121, a = 78.5, b = 150.0, c = 279.3. The structure reveals aspects of the catalytic mechanism and suggests explanations for the effects of drug resistance mutations. Papillomavirus L1. We have begun studies of crystals of recombinant pentamers of HPV L1. There are several crystal forms, all with very large unit cells.